Compare to: http://www.youtube.com/watch?v=4wInhzX_ym0&feature=player_detailpage#t=128s
That is the same exact part on Now I'm Here: The first link is the DVD, while the second link is the audience recording. At around 3:00-3:05, Freddie sings "Go Johnny Go" on the DVD version (you can see him sing, and he has the mic by his mouth). If you listen to the same area on the audience recording, you can't hear him sing that! Did Freddie have mic problems at that part?
On a closer listen, I can very faintly hear him sing that line on the audience recording, but I think the mic had some issues!
I always knew I was a star And now, the rest of the world seems to agree with me-Freddie Mercury